The present invention relates to improvement in a method of and an apparatus for producing hydrogen by a reforming reaction. In particular, it relates to providing an auto-oxidation and internal heating type reforming method and apparatus for hydrogen production.
So far in producing hydrogen, a reforming method and apparatus using a reforming reaction has advantageously been adopted in which a mixture of a hydrocarbon or an aliphatic alcohol with water vapor is fed onto and contacted with a reforming catalyst. In such methods and apparatus, it is customary that a quantity of heat needed for the reforming reaction is provided externally via wall surfaces of the reforming reactor.
In such conventional methods and apparatus as described, the necessary amount of heat for the reforming reaction is supplied externally via the wall surfaces of the reforming reactor with a sensible heat of a combustion gas burnt outside of the reforming reactor or a sensible heat of a heating medium. It has therefore been necessary that an external combustion furnace or burner unit for heat supply or thermo-circulating unit for the heating medium or thermal catalyst be separately provided. As a result, the entire apparatus has had to be large in size and yet it has been difficult to obtain well satisfactory thermal efficiency. Also, in the case of hydrocarbons use, methane whose reforming reaction temperature is required for 700 to 750xc2x0 C. is usually used. And if methane is heated externally to reach that temperature in the reforming reactor, the wall surfaces of the reforming reactor must be limited in temperature to 1000xc2x0 C. or less, otherwise the material that makes up those wall surfaces tends to deteriorate, rendering the reforming reactor not usable over a long period of time and thus causing a difficulty in its workability.
The present invention is contrived to solve the foregoing problems and it is an object of the present invention to provide a reforming method for hydrogen production which makes a reforming reactor apparatus compact, which largely reduces energy cost needed for reforming, and which is capable of bringing development of NOx, an environmental pollutant, almost or unlimitedly to zero. It is also an object of the present invention to provide a reforming apparatus for carrying out such a method.
In order to achieve the objects mentioned above there is provided in accordance with the present invention in a first aspect thereof an auto-oxidation and internal heating type reforming method for hydrogen production for use in a process in which a gaseous mixture of a hydrocarbon or an aliphatic alcohol with water vapor is fed into contact with a mass of a reforming catalyst to bring about a reforming reaction of the gaseous mixture therewith to produce hydrogen, wherein the method comprises the steps of: admixing a small amount of an oxidizing catalyst with the said reforming catalyst in the said mass; and admixing a small amount of oxygen with the gaseous mixture of the hydrocarbon or aliphatic alcohol with water vapor, whereby a portion of the hydrocarbon or aliphatic alcohol is exothermally oxidized to generate an amount of heat required to reform the gaseous mixture of the hydrocarbon or aliphatic alcohol with water vapor.